add JsExtensions.kt

app/src/main/java/io/legado/app/utils/JsExtensions.kt

@@ -0,0 +1,68 @@
+@file:Suppress("unused")
+
+package io.legado.app.utils
+
+import org.mozilla.javascript.*
+
+/**
+ * 禁止在js里删除文件
+ * 参考 https://codeutopia.net/blog/2009/01/02/sandboxing-rhino-in-java/
+ */
+fun ContextFactory.eval(jsStr: String, scriptObjects: Map<String, Any>): Any {
+    val ctx = this.enterContext()
+    ctx.optimizationLevel = -1
+    ctx.setClassShutter {
+        when {
+            it.startsWith("java.io") -> false
+            else -> true
+        }
+    }
+    val scope: Scriptable = ctx.initStandardObjects()
+    for (name in scriptObjects.keys) {
+        val obj = scriptObjects[name]
+        if (obj is Boolean) {
+            scope.put(name, scope, obj)
+        } else if (obj != null) {
+            val jsArgs = Context.toObject(obj, scope)
+            scope.put(name, scope, jsArgs)
+        }
+    }
+    scope.delete("Packages")
+    return try {
+        ctx.evaluateString(scope, jsStr, null, 1, null)
+    } catch (e: RhinoException) {
+        e.printStackTrace()
+        e.toString()
+    } finally {
+        Context.exit()
+    }
+}
+
+class SandboxNativeJavaObject(scope: Scriptable?, javaObject: Any?, staticType: Class<*>?) :
+    NativeJavaObject(scope, javaObject, staticType) {
+    override fun get(name: String, start: Scriptable): Any {
+        return when (name) {
+            "getClass", "delete" -> NOT_FOUND
+            else -> super.get(name, start)
+        }
+    }
+}
+
+class SandboxWrapFactory : WrapFactory() {
+    override fun wrapAsJavaObject(
+        cx: Context?,
+        scope: Scriptable?,
+        javaObject: Any?,
+        staticType: Class<*>?
+    ): Scriptable {
+        return SandboxNativeJavaObject(scope, javaObject, staticType)
+    }
+}
+
+class SandboxContextFactory : ContextFactory() {
+    override fun makeContext(): Context {
+        val cx = super.makeContext()
+        cx.wrapFactory = SandboxWrapFactory()
+        return cx
+    }
+}